Clamping arrangement for cascade transformer



March 24, 1959 G. CAMILLI ET AL 2,879,488

CLAMPI-NG ARRANGEMENT FOR CASCADE TRANSFORMER Filed Sept. 18, 1957 II IIIIII United States Patent O CLAMPING ARRANGEMENT FOR CASCADE TRANSFORMER Application September 18, 1957, Serial No. 684,675

7 Claims. (Cl. 336-90) This invention relates to stationary eelctrical induction apparatus, and more in particular to an improved means for clamping the components of cascade transformers of the type comprising a plurality of individual transformer units separated by insulating shells.

A plurality of individual transformer units connected in cascade have frequently been employed for such applications as high voltage potential transformers in order to reduce the necessity for expensive insulation required in a single large transformer employed for the same purpose. A typical cascade transformer arrangement is clisclosed in U.S. Letters Patent 2,113,421, which issued on an application of G. Carnilli and W. Linch and is assigned to the assignee of the present invention. In this patent the cascade transformer is disclosed as being comprised of a plurality of individual transformer units stacked axially of the transformer and separated by a plurality of insulating shell members. Each of the transformer units comprises a magnetic core extending transversely of the axis of the transformer into a casing or tank. The insulating shell members abut the casings, and in order to hold the structure together the ends of the insulating shells are tapered to engage frustoconical clamping rings bolted on the casings. The magnetic cores of the individual transformer units are supported from the casings. The clamping arrangement between the ends of the insulating shells and the casings provides the sole mechanical support for the transformer. The joints between the casings and insulation are sealed to prevent loss of dielectric fluid lling the transformer.

While the mechanical support thus provided was satisfactory once the transformer had been installed, considerable difficulty was experienced in the transportation of the assembled transformer. Since the clamping arrangement did not provide suicient strength in tension, it was necessary to lift the transformer from its base and provide bracing to hold the transformer in an upright position. The severe vibration experienced in transporting the transformer, however, frequently resulted in the developing of the leaks at the clamping rings, and also in the breakage of the ceramic shells.

It is therefore an object of this invention to provide an improved clamping arrangement for a cascade transformer.

It is a further object to provide a clamping arrangement for a cascade transformer, the clamping arrangement providing sufficient mechanical strength for the assembly that it is not necessary to support the transformer from its base, and also that it is not necessary that the transformer be transported in an upright position.

A still further object of this invention is to provide a clamping arrangement for a cascade transformer wherein compressional forces are exerted between the insulating shells and separate transformer units, the compressional force not being dependent upon frustoconical forming of the ends of the insulating shells separating the individual transformer units.

Briefly stated, in accordance with one embodiment of' 2,879,488 ce Patented Mar. 24, 1959 this invention, we provide means for mechanically clamping the components of a transformer of the type having a plurality of individual transformer units separated by insulating shells. The clamping means comprises elongated insulating members preferably having arcuate cross sections and extending axially of the transformer through the insulating shells and winding windows of the transformer units. Clamping means are provided on the ends of the elongated insulating members for applying compressional clamping force between the transformer units and insulating shells.

While the specification concludes with claims particularly pointing out and distinctly'claiming the subject matter which we regard as our invention, it is believed that the invention will be better understood from the following description taken in connection with the accompanying drawing.

In the drawing:

Fig. 1 is a partially cross sectional side view of a cascade transformer according to the present invention;

Fig. 2 is a partially cross sectional view of the top of the transformer of Fig. l;

Fig. 3 is an enlarged view of a clamp member employed in the transformer of Figs. 1 and 2;

Fig. 4 is an enlarged cross sectional view of the lower clamping arrangement of the transformer of Fig. 1; and

Fig. 5 is an enlarged cross sectional view of the upper clamping arrangement of the transformer of Fig. 1.

Referring now to the drawing, and more particularly to Fig. 1, therein is illustrated a cascade transformer comprising three separate individual transformer units 10, 11 and 12. The precise number of transformer units employed is not material from the standpoint of the present invention, nor is the manner in which the transformer units are electrically connected. As an example, however, the transformer units may be electrically connected in the manner illustrated in the above-mentioned Camilli and Linch patent. The lower transformer unit 10 is mounted on a base 13, and is separated from the intermediate transformer unit 11 by a hollow insulating shell 14 extending axially of the transformer. The intermediate transformer unit 11 is separated from the upper transformer unit 12 by another hollow insulating member 15 similarly extending axially of the transformer and the upper transformer unit 12 is separated from an upper terminal assembly 16 by another insulating shell 17 extending axially of the transformer. The transformer may be lled with a dielectric insulating liquid or fluid according to the conventional practice.

Each of the transformer units 10, 11 and 12 is comprised of a magnetic core 20 having a central winding leg 21 joined at its ends by a pair of yoke portions 22 extending transversely of the axis of the transformer into a tank 23. As vwill be more clearly seen in Fig. 2, the center leg and yoke portions of the core define a pair of winding windows 24 extending axially of the transformer. The center leg 21 is provided with electrical windings 25 partly filling the Winding windows 24. The magnetic core 20 is preferably formed of a pair of opposed D-shaped cores of wound magnetic strip material, although the core may alternatively be formed by other means such as, for example, a plurality of layers of flat stacked laminations of magnetic material.

Referring again to Fig. l, each tank 23 is preferably comprised of an annular member 26 radially surrounding the magnetic core 20 and having a pair of radially inwardly extending flanges 27 axially engaging the sides of the magnetic core. The flanges 27 should be insulated from the core 20 if a wound core is employed, as by annular insulation 28, in order to prevent shorting of the core laminations. To simplify fabrication, the flanges 27 may be welded to the annular member 26.

Annular sealing gaskets 30 are provided in grooves in the faces of the anges 27 engaging the hollow insulating members to prevent loss of dielectric uid from the transformer. f

IElongated insulating members Alil-,',preferably having arcuate cross sections, are provided extending axially of the transformer through theinsulating shells and windows 24 of the transformers units. The upper ends of the members 31 extend above the uppermost insulating shell 17, and the lower ends of the members 31 extend into the transformer base 13. Arcuate clamping brackets 32 having radially outwardly extending anges 33 are bolted to the upper and lower ends of the insulating members 31. As illustrated in Fig. 3, the anges 33 are provided with a plurality of tapped holes 34, and bracing webs 35 may be provided between the ang'es 33 and the portion 3.6 bolted to the insulating members 31. Y

- The lowermost flange 27 of the lower transformer unit abuts the upper side of an annular plate 40 (Fig. 4) on the top of the transformer base 13. Bolts 41 in the holes 34 in the flanges 33 of the clamping brackets engage the underside of plate 40. Similarly, an annular plate 42 (Fig. 5) is provided'abutting the upper end of the uppermost parallel insulating member 17, and bolts 43 in the threaded4 holesin the upper clamping bracket engage the upper side of the plate42.

The top of the transformer may be sealed by a cap 44 bolted to the plate 42 and connected to the high voltage terminal 45. v 1

l By adjusting the bolts, 41 and 43, compressionaliclampingforce is placed on the,A outer structure of the transformer comprising the hollow insulating shells 'and the transformer unit tanks. These compressional forces ensure Huid-tight seals betweenA the transformer tanks and the hollow insulating members, and also provide mechanical support Vfor the transformer. By employingthe internal .insulating members 31, it is unnecessary to provide clamping rings and tapers on the ends of the insulating shells to seal the transformer. The resultant structure is thereby more readily and economically fabricated, and the additional mechanical support pro vided by the arrangement reduces the danger of damage to the structure during shipment. For example, it has been found that suicient mechanical support is provided that the transformer may be lifted from the top terminal assembly without danger of damage. The transformer may also be shipped or stored in a horizontal position.

In addition to providing mechanical support for the transformer, the elongated members 31 also serve as an insulating medium between the transformer unit windings 25 and the core yokes 22.

f It will be understood, of course, that, while the form of the invention herein shown and described constitutes the preferred embodiment of the invention, it is not intended herein to illustrate all of the possible equivalent forms or ramifications thereof. It will also be understood that the words used are words of description rather than of limitation, and that various changes may be made without departing from the spirit or scope of the invention herein disclosed, and it is aimed in the appended claims to cover all such changes as fall within the true spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. Means for mechanically clamping the components of a transformer of the type having a plurality of individual transformer units separated by insulating shells, said transformer units each having a magnetic core defining at least one winding window said means comprising elongated insulating members extending axially of said transformer through said shells and the winding windows of said transformer units, and clamping means on the ends of said insulating members for applying compressional clamping force between said transformer units and insulating shells.

2. A transformer comprising a plurality of individual transformer units, each of said units comprising a mag'- netic core defining at least one winding window and having a central winding leg extending transversely of the axis of said transformer and joined at its ends by a pair of yoke portions, tank means surrounding said portions, insulating shell means extending axially of said transformer between said tank means, elongated insulating members extending axially of said transformer through said shell means and the windows of said magnetic cores, and clamping means on the ends of said insulating members to provide compressional clamping force between said shell means and tank means.

3. A transformer comprising a plurality of individual transformer units, each of said units comprising a magnetic core with a central winding leg and a pair of yoke portions defining a pair of winding windows extending axially of said transformer, tank means surrounding said yoke portion, insulating shell means extending axially of said transformer between said tank means, elongated arcuate cross section insulating members extending axially of said transformer through said shell means and winding windows, and clamping means on the ends of said insulating members for applying compressional force between said tank means and insulating shell means.

.4. A transformer comprising a plurality of individual transformer units, each of said units comprising a magnetic core with a central winding leg joined at its ends by a pair of yoke members and defining a pair of winding windows extending axially of said transformer, separate annular tank means having channel shaped cross sections surrounding each unit core, insulating shell means'extend= ingbetween said tank means, said tank means and insulat# ing shell means being coaxial with said transformer,

elongated arcuate cross section insulating means extend;

ing axially of said transformer through said insulating shell means and winding windows, and clamping means on the ends of said insulating members for applying corn# pressional clamping force between said tank means and insulating shell means.

5. A cascade transformer comprising a. plurality of cascade connected individual transformer units axially separated from each other with respect to said cascade transformer by a plurality of insulating shells, each of said transformer units comprising a magnetic core having arcuate yoke portions extending transversely of the axis of said cascade transformer into annular tank means vand a central leg portion extending transversely of the axis of said cascade transformer, electrical windings surrounding said central leg portion, said yoke and leg portion defining a pair of winding windows, said tanks having channel shaped cross sections, elongated arcuate cross section insulating members extending through said shells and winding windows, and clamp means on the ends of said insulating members for applying compressional clamping forces to hold said shells and tanks together.

6. A cascade transformer comprising a plurality of cascade connected individual transformer units axially separated from each other with respect to said cascade transformer by a plurality of insulating shells, each of said transformer units comprising a magnetic core having arcuate yoke portions extending transversely of the axis of said cascade transformer and being radially surrounded by annular tank means, said tank means having inwardly extending flange means axially engaging said yoke portions, said core having a winding leg portion extending transversely of the axis of said cascade transformer, said yoke and leg portions defining a pair of winding windows, elongated arcuate cross section insulating members extending through said shells and winding windows, and clamp means on the ends of said insulating members and engaging end portions of said cascade transformer for clamping said shells against the flanges of said tank means.

7. A cascade transformer comprising a plurality of cascade connected individual transformer units axially separated from each other with respect to said cascade transformer by a plurality of insulating shells, each of said magnetic cores comprising a pair of opposed D- shaped wound magnetic core with common electrical windings on the straight portions of the cores, the arcuate portions of said cores extending transversely of the axis of said cascade transformer and being radially surrounded by an annular tank member, said tank member having inwardly extending tlanges axially engaging the arcuate portions of said core, a pair of elongated arcuate cross 10 section insulating members extending axially of said transformer through said shells and the winding windows of said cores, and clamp means on the ends of said insulating members providing axial clamping forces for holding 5 said shells against the flanges of said tank members.

Camilli et al Apr. 5, 1938 Vienneau Sept. 12, 1950 

